1998 Dodge Dakota water pump noise

I replaced the water pump a yr ago, and it seems that when it is moist either rain or snow damp weather there seems to be a squeeling noise coming from the engine, I have tried a make shift stethescope to isolate the area but being the fan is there im notgoin to get that close. When the truck warms up it goes away or gets quieter. Any ideas on what it could be? I replaced the serpen belt as I thought maybe that was the prob but it still makes the noise. Thank you in advance for any assistance